Systems employing evacuated chambers have been utilized in the past for various types of processing requiring a full or partial vacuum. Vacuum type systems requiring vacuum chambers are used especially with electron microscopes, ion-micro analyzers, treatments using materials such as oil, or the fabrication of electronic components and circuits. An example of such a vacuum system is shown in U.S. Pat. No. 3,340,146. In general, these vacuum systems are utilized for controlling contamination during processing. Vacuum systems are also frequently encountered in connection with apparatus such as particle accelerators which are used for a variety of industrial processing, as well as for research purposes.
Uranium separation is another area where vacuum processing is utilized. As described in U.S. Pat. No. 3,772,519 issued Nov. 13, 1973, to Richard H. Levy, et al, a method of ion separation is described in which in one embodiment, uranium U-235 is separated from U-238 by means of laser stimulation in an elongated channel to produce the requisite U-235 ionization within a vacuum chamber. This is followed by separation through the utilization of crossed magnetic and electric fields in which the ionized U-235 is directed to radially extending electrodes, while U-238 is collected at the top of the vacuum chamber.
In commercial processing it is important to be able to recover not only the collected U-235 but also the tailing which includes U-238. In order to do so, it is necessary to periodically remove both the electrode bearing structure and the tailing structure from the interior of the vacuum chamber at all points along the channel length. In existing apparatus this has been difficult to accomplish because of the size and weight of the collecting structure relative to chamber access port size, and because the removal process is preferably performed without destroying the vacuum of the chamber. This is further complicated by the substantial channel length.
In addition, it is also desirable to be able to repair or replace the vaporizer assembly without destroying the vacuum within the chamber. A movable cask for use with radioactive vacuum chambers is disclosed in U.S. Pat. No. 3,489,298. However, the cask as described therein is not suitable for removing or supporting the vaporizer assemblies or the extractor assemblies of a uranium enrichment process because of its small size and because of its lack of appropriately adapted components. The vaporizer utilized in laser isotope separation is typically a linear vaporizer of substantial length further complicating its removal from and replacement in the vacuum chamber.